While exploring the lower levels, the UNSC forces eventually come across a sealed door, locked down by the Covenant to prevent the escape of the Flood. With increased curiosity the UNSC open the door and explore the room. The Flood attacked the UNSC forces and begin to infect any available host present.[1]

Later on, John-117 arrived near V933s crash site on board Echo 419. He then entered the lightly guarded structure, being watched by the Flood. After entering the Containment Room, he found PrivateJenkins' helmet with a built in video camera. After seeing the gruesome events through the eyes of Jenkins, the remaining Flood spewed out of nearby doors. John-117 proceeds after the remaining UNSC forces, combating Infection and Combat forms. John-117 soon catches up with the remaining UNSC forces, who are advised by Echo-419 to take refuge at a nearby structure, the Library.[1]

The crashed Spirit dropship is captured by the Flood, who use it to escape the ringworld. Other Flood forces in the vicinity of the Library are wiped out, though the Flood that already escaped the Containment facility spread across the Installation, infecting any appropriate hosts.